Question

This is my starting regex that is not working:

'/^(DO)(?<cmd>.{1,6})$/'

The expression should match any string starting with ‘DO’, the string after ‘DO’ must be of minimum 1 and max 6 characters in length.

What I expect:

 DO // NOT A MATCH
 DO123 // MATCH
 DOaaa123 // MATCH
 DOaaa123b // NOT A MATCH

---

?<cmd>

is a named subpattern: matches are stored as associative array.

Answer 1

Seems like it’s a back compatibility problem, although the documentation changelog says:

5.2.2 Named subpatterns now accept the syntax (?) and (?’name’) as well as (?P). Previous versions accepted only (?P).

Using PHP 5.4.8, windows IIS

This works fine:

'/^(DO)(?P<cmd>.{1,6})$/'